Long-Term Changes in the Wintering Population of the Dalmatian Pelican along the Black Sea-Mediterranean Flyway

Abstract

Understanding spatiotemporal dynamics in wildlife populations is of paramount importance for their effective conservation, however longitudinal studies are relatively scarce for most animal groups. Waterbirds are an exception however, since midwinter surveys have been implemented in most areas of the world for over four decades. The Dalmatian Pelican Pelecanus crispus is a globally threatened emblematic wetland species of the Palearctic, with a wide distribution in Europe and Asia. Its global population is divided into three distinct groups that coincide with the Black Sea-Mediterranean Flyway, the Central Asian Flyway and the East Asian Flyway. In this study we used International Waterfowl Census data to assess long-term changes in the wintering population of the Dalmatian Pelican pertaining to the Black Sea-Mediterranean Flyway. We report national and regional population trends in SE Europe and Turkey and explore spatiotemporal patterns in the wintering numbers and distribution of the species in relation to climate variability during the last two decades. Our key findings suggest that during the past 30 years the abundance of wintering Pelicans increased across the entire study area. Within the eastern subpopulation this increase was most accentuated in the northern edge of the species' wintering distribution, which was associated with a local warming trend, and was coupled with a north-eastern shift in the distribution pattern, yet not driven by climate conditions. Other contributing factors, such as winter site fidelity, local food availability, finer scale climatic and habitat conditions, but also carry-over effects should be considered in future studies. Given the advancement of first laying dates in Dalmatian Pelicans in almost all breeding sites and the strict timing of IWC counts, we also propose the implementation of species-specific winter surveys, independently from IWC, to obtain a more thorough understanding of the dynamics of the Dalmatian Pelican's wintering population.